In our previous patents, for instance, U.S. Pat. Nos. 7,100,622 and 6,206,016, we described various devices used to scarify pipes, passageways, and such. These devices are referred to in the art as “scarifying devices” or just “scarifiers.” Such previously described scarifiers are self-propelled or mounted on a vehicle so that the scarifier and its means of propulsion are integrated into one unit. While self-propelled scarifiers have some advantages, they also have a number of disadvantages. For instance, their size and mass make them difficult to transport and to position in the pipe being scarified. Here we disclose a novel scarifying system including a stand-alone pipe tractor that propels a scarifier along the pipe and also provides power and control functions.